206 research outputs found
INFLUENCE OF BONDINGS FOR THE LACING, BACKERS AND HEEL COUNTERS OF THE FOOTWEAR IN THE PRONOSUPINATION MOVEMENT IN RUNNING
The relationship between the excessive pronosupination of the rearfoot and some of the injuries in runners has been widely described in the 1it.erature (Bates, Cavanagh, Clement, Nigg, Stacoff). In the same way, the influence of the midsole design and the material used for its construction in the pronosupinatlon movement of the font has been analyzed by different authors. Nevertheless, the influence of other elements as heel counters, backers and bondings for the lacing, in the upper vamp that covers the foot has not beer! enough studied. In order to determine the effect of the above mentioned elements some experiments have been developed with a group of 10 runners selected because of their tendency to excessive pronation. Seven prototypes of running shoes with identical characteristics referred to construction of midsole and sole, but presenting different elements in the upper vamp materials designed to control the pronosupination of the foot, were successively weared by each runner selected The experiences consisted of filming three consecutive running supports done on a treadmill at an speed of 8 miles per hour (12.8 Km per hour). The speed of filmation of the camera was fixed at 85 images per second. After digitizing the Images obtained and the processing of the data, with an specially designed software for that purpose, the following results were obtained: - the prototypes not including control systems in the upper vamp generate the higher levels of pronation and torsion during the contact - isolated use of external heel counters does not permit to assure a good control of the- pronation movement but, however, has a rigidizing effect reducing the torsion movement. - including a post in the internal face of the rearfoot joined to the external heel counter showed a great effectiveness i n the control of the pronation reducing the torsion movement. - the location of backers fort he bonding of the lacing helps to reduce the pronation movement without rigidizing excesivelly the shoe
Magnetically induced splitting of a giant vortex state in a mesoscopic superconducting disk
The nucleation of superconductivity in a superconducting disk with a Co/Pt
magnetic triangle was studied. We demonstrate that when the applied magnetic
field is parallel to the magnetization of the triangle, the giant vortex state
of vorticity three splits into three individual F0-vortices, due to a
pronounced influence of the C3 symmetry of the magnetic triangle. As a result
of a strong pinning of the three vortices by the triangle, their configuration
remains stable in a broad range of applied magnetic fields. For sufficiently
high fields, F0-vortices merge and the nucleation occurs through the giant
vortex state. The theoretical analysis of this novel reentrant behaviour at the
phase boundary, obtained within the Ginzburg - Landau formalism, is in
excellent agreement with the experimental data.Comment: to be published in Phys. Rev. B - Rapid. Com
Changes in the electrical transport of ZnO under visible light
Complex impedance spectroscopy data in the frequency range 16Hz < f < 3 MHz
at room temperature were acquired on pure ZnO single crystal and thin film. The
measured impedance of the ZnO samples shows large changes with time after
exposure to or covering them from visible light. At fixed times
Cole-Cole-diagrams indicate the presence of a single relaxation process. A
simple analysis of the impedance data allows us to obtain two main relaxation
times. The behavior for both, ZnO crystal and thin film, is similar but the
thin film shows shorter relaxation times. The analysis indicates the existence
of two different photo-active defects with activation energies between ~0.8 eV
and ~1.1 eV.Comment: 11 pages, 9 figures. Solid state communications, in pres
Segregated tunneling-percolation model for transport nonuniversality
We propose a theory of the origin of transport nonuniversality in disordered
insulating-conducting compounds based on the interplay between microstructure
and tunneling processes between metallic grains dispersed in the insulating
host. We show that if the metallic phase is arranged in quasi-one dimensional
chains of conducting grains, then the distribution function of the chain
conductivities g has a power-law divergence for g -> 0 leading to nonuniversal
values of the transport critical exponent t. We evaluate the critical exponent
t by Monte Carlo calculations on a cubic lattice and show that our model can
describe universal as well nonuniversal behavior of transport depending on the
value of few microstructural parameters. Such segregated tunneling-percolation
model can describe the microstructure of a quite vast class of materials known
as thick-film resistors which display universal or nonuniversal values of t
depending on the composition.Comment: 8 pages, 5 figures (Phys. Rev. B - 1 August 2003)(fig1 replaced
Gender Differences in Leg Stiffness and Stiffness Recruitment Strategy During Two-Legged Hopping
The authors compared leg stiffness (KVERT), muscle activation, and joint movement patterns between 11 men and 10 women during hopping. Physically active and healthy men and women performed continuous 2-legged hopping at their preferred rate and at 3.0 Hz. Compared with men, women demonstrated decreased KVERT; however, after the authors normalized for body mass, gender differences in KVERT were eliminated. In comparison with men, women also demonstrated increased quadriceps and soleus activity, as well as greater quadriceps-to-hamstrings coactivation ratios. There were no significant gender differences for joint movement patterns (p > .05). The relationship between the observed gender differences in muscle recruitment and the increased risk of anterior cruciate ligament injury in women requires further study
On the rotational dynamics of the Rattleback
The Rattleback is a very popular science toy shown to students all over the
world to demonstrate the non-triviality of rotational motion. When spun on a
horizontal table, this boat-shaped object behaves in a peculiar way. Although
the object appears symmetric, the dynamics of its motion seem very asymmetric.
When spun in the preferred direction, it spins smoothly, whereas in the other
direction it starts to oscillate wildly. The oscillation soon dies out and the
rattleback starts to spin in the preferred way. We will construct and go
through an analytical model capable of explaining this behaviour in a simple
and intelligible way. Although we aim at a semi-pedagogical treatise, we will
study the details only when they are necessary to understand the calculation.
After presenting the calculations we will discuss the physical validity of our
assumptions and take a look at more sophisticated models requiring numerical
analysis. We will then improve our model by assuming a simple friction force.Comment: 17 pages and 2 figures, typos corrected, some minor additions and
rewording
General practitioners’ perspectives on campaigns to promote rapid help-seeking behaviour at the onset of rheumatoid arthritis
Objective. To explore general practitioners’ (GPs’ ) perspectives on public health campaigns to encourage people with the early symptoms of rheumatoid arthritis (RA) to seek medical help rapidly. Design. Nineteen GPs participated in four semistructured focus groups. Focus groups were audio-recorded, transcribed verbatim, and analysed using thematic analysis. Results. GPs recognised the need for the early treatment of RA and identified that facilitating appropriate access to care was important. However, not all held the view that a delay in help seeking was a clinically significant issue. Furthermore, many were concerned that the early symptoms of RA were often non-specific, and that current knowledge about the nature of symptoms at disease onset was inadequate to inform the content of a help-seeking campaign. They argued that a campaign might not be able to specifically target those who need to present urgently. Poorly designed campaigns were suggested to have a negative impact on GPs’ workloads, and would “clog up” the referral pathway for genuine cases of RA. Conclusions. GPs were supportive of strategies to improve access to Rheumatological care and increase public awareness of RA symptoms. However, they have identified important issues that need to be considered in developing a public health campaign that forms part of an overall strategy to reduce time to treatment for patients with new onset RA. This study highlights the value of gaining GPs’ perspectives before launching health promotion campaigns
Piezoresistivity and conductance anisotropy of tunneling-percolating systems
Percolating networks based on interparticle tunneling conduction are shown to
yield a logarithmic divergent piezoresistive response close to the critical
point as long as the electrical conductivity becomes nonuniversal. At the same
time, the piezoresistivity or, equivalently, the conductivity anisotropy
exponent remains universal also when the conductive exponent is not,
suggesting a purely geometric origin of . We discuss our results in
relation to the nature of transport for a variety of materials such as
carbon-black--polymer composites and RuO_2-glass systems which show
nonuniversal transport properties and coexistence between tunneling and
percolating behaviors.Comment: 6 pages, 3 figures, Added discussion on experiment
Ultrasound-diagnosed disorders in shoulder patients in daily general practice: a retrospective observational study
Differences Among Health Care Settings in Utilization and Type of Physical Rehabilitation Administered to Patients Receiving Workers’ Compensation for Musculoskeletal Disorders
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